While translating the actions of low-dose tacrolimus on FoxP3 activation in PCOS awaits further investigations, we believe that, at least in part, through this plausible stimulatory effect on FoxP3, low-dose tacrolimus is capable of inducing the periconceptional expansion of the CD4+CD25+CD127low Tregs in a murine model of PCOS [128]. This evidence concerns the gene CD4 and polycystic ovary syndrome.